// Copyright 2017, VIXL authors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//   * Neither the name of ARM Limited nor the names of its contributors may be
//     used to endorse or promote products derived from this software without
//     specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

extern "C" {
#include <sys/mman.h>
}

#include "code-buffer-vixl.h"
#include "utils-vixl.h"

namespace vixl {


    CodeBuffer::CodeBuffer(size_t capacity)
            : buffer_(NULL),
              managed_(true),
              cursor_(NULL),
              dirty_(false),
              capacity_(capacity) {
        if (capacity_ == 0) {
            return;
        }
#ifdef VIXL_CODE_BUFFER_MALLOC
            buffer_ = reinterpret_cast<byte*>(malloc(capacity_));
#elif defined(VIXL_CODE_BUFFER_MMAP)
            buffer_ = reinterpret_cast<byte*>(mmap(NULL,
                                                   capacity,
                                                   PROT_READ | PROT_WRITE,
                                                   MAP_PRIVATE | MAP_ANONYMOUS,
                                                   -1,
                                                   0));
#else
#error Unknown code buffer allocator.
#endif
        VIXL_CHECK(buffer_ != NULL);
        // Aarch64 instructions must be word aligned, we assert the default allocator
        // always returns word align memory.
        VIXL_ASSERT(IsWordAligned(buffer_));

        cursor_ = buffer_;
    }


    CodeBuffer::CodeBuffer(byte *buffer, size_t capacity)
            : buffer_(reinterpret_cast<byte *>(buffer)),
              managed_(false),
              cursor_(reinterpret_cast<byte *>(buffer)),
              dirty_(false),
              capacity_(capacity) {
        VIXL_ASSERT(buffer_ != NULL);
    }


    CodeBuffer::~CodeBuffer() {
        VIXL_ASSERT(!IsDirty());
        if (managed_) {
#ifdef VIXL_CODE_BUFFER_MALLOC
            free(buffer_);
#elif defined(VIXL_CODE_BUFFER_MMAP)
            munmap(buffer_, capacity_);
#else
#error Unknown code buffer allocator.
#endif
        }
    }


#ifdef VIXL_CODE_BUFFER_MMAP
    void CodeBuffer::SetExecutable() {
      int ret = mprotect(buffer_, capacity_, PROT_READ | PROT_EXEC);
      VIXL_CHECK(ret == 0);
    }
#endif


#ifdef VIXL_CODE_BUFFER_MMAP
    void CodeBuffer::SetWritable() {
      int ret = mprotect(buffer_, capacity_, PROT_READ | PROT_WRITE);
      VIXL_CHECK(ret == 0);
    }
#endif

#if defined(__ANDROID_API__) && __ANDROID_API__ < 21
    char *
    stpcpy(char *to, const char *from) {
        for (; (*to = *from) != '\0'; ++from, ++to);
        return (to);
    }
#endif

    void CodeBuffer::EmitString(const char *string) {
        VIXL_ASSERT(HasSpaceFor(strlen(string) + 1));
        char *dst = reinterpret_cast<char *>(cursor_);
        dirty_ = true;
        char *null_char = stpcpy(dst, string);
        cursor_ = reinterpret_cast<byte *>(null_char) + 1;
    }


    void CodeBuffer::EmitData(const void *data, size_t size) {
        VIXL_ASSERT(HasSpaceFor(size));
        dirty_ = true;
        memcpy(cursor_, data, size);
        cursor_ = cursor_ + size;
    }


    void CodeBuffer::UpdateData(size_t offset, const void *data, size_t size) {
        dirty_ = true;
        byte *dst = buffer_ + offset;
        VIXL_ASSERT(dst + size <= cursor_);
        memcpy(dst, data, size);
    }


    void CodeBuffer::Align() {
        byte *end = AlignUp(cursor_, 4);
        const size_t padding_size = end - cursor_;
        VIXL_ASSERT(padding_size <= 4);
        EmitZeroedBytes(static_cast<int>(padding_size));
    }

    void CodeBuffer::EmitZeroedBytes(int n) {
        EnsureSpaceFor(n);
        dirty_ = true;
        memset(cursor_, 0, n);
        cursor_ += n;
    }

    void CodeBuffer::Reset() {
#ifdef VIXL_DEBUG
        if (managed_) {
          // Fill with zeros (there is no useful value common to A32 and T32).
          memset(buffer_, 0, capacity_);
        }
#endif
        cursor_ = buffer_;
        SetClean();
    }


    void CodeBuffer::Grow(size_t new_capacity) {
        VIXL_ASSERT(managed_);
        VIXL_ASSERT(new_capacity > capacity_);
        ptrdiff_t cursor_offset = GetCursorOffset();
#ifdef VIXL_CODE_BUFFER_MALLOC
        buffer_ = static_cast<byte*>(realloc(buffer_, new_capacity));
        VIXL_CHECK(buffer_ != NULL);
#elif defined(VIXL_CODE_BUFFER_MMAP)
        buffer_ = static_cast<byte*>(
            mremap(buffer_, capacity_, new_capacity, MREMAP_MAYMOVE));
        VIXL_CHECK(buffer_ != MAP_FAILED);
#else
#error Unknown code buffer allocator.
#endif

        cursor_ = buffer_ + cursor_offset;
        capacity_ = new_capacity;
    }


}  // namespace vixl
